Refuse a Java file that is not UTF-8 instead of rewriting it

new String(bytes, UTF_8) turned each byte that is not UTF-8 into
U+FFFD, and --replace wrote the result back: an "é" saved as Latin-1
became EF BF BD, and the exit code was 0. Files.readString throws on
such a byte, so the file is reported as one Main could not read and
stays as it is, with exit code 2.

Standard input still decodes with replacement.

Author: abashev

open-java-format/src/main/java/com/palantir/javaformat/java/Main.java

@@ -146,7 +146,7 @@ private int formatFiles(
             Path path = Paths.get(fileName);
             String input;
             try {
-                input = new String(Files.readAllBytes(path), UTF_8);
+                input = Files.readString(path);
                 inputs.put(path, input);
                 results.put(path, executorService.submit(new FormatFileCallable(parameters, input, options)));
             } catch (IOException e) {